\documentclass{article}
\usepackage{amssymb,amsmath,amscd,concmath}
\pagestyle{empty}
\begin{document}
\begin{equation*}
a = b
a = b\mbox{ and multipying for} b
a b = b^2
a b = b^2 (-b^2)
\end{equation*}
\end{document}
